Chapter 6 - Cross Section Elements

6.5. Curbs – Outside Shoulders

6.5.5. Raised Chanellizing Islands

Raised channelizing islands help control and direct the movement of traffic by reducing excess pavement areas, and channelizing turning movements at intersections. In urban locations, a sloped curb is generally used in conjunction with striping to delineate the island. In rural locations where higher speeds are likely, islands are typically delineated with a sloped curb and offset appropriately. In areas with crosswalks where raised islands will be used for pedestrian refuge, the geometry of the intersection and the right turn lanes may need to be modified to ensure that the raised islands are large enough to accommodate ramps and pedestrian refuge areas along with support for pedestrian signals and control buttons, that are compliant with the Americans with Disabilities Act (ADA)* guidelines.

Raised islands should be offset from the travel lane, as shown in the current GDOT Regulations for Driveway and Encroachment Control.  Refer to Chapter 9 of the current AASHTO Green Book for additional information. Raised islands should be offset 4-ft. from travel lanes when posted speeds are < 45 mph and 10-ft. from travel lanes when posted speeds are > 45 mph.

* Visit the following FHWA web page for additional information relating to Americans with Disabilities Act (ADA) requirements: http://www.fhwa.dot.gov/environment/te/te_ada.htm